Forms Data Controls :: Nested Gridview ... Find The Parent Control Id

i have a parent gridview,It has child gridview in every row.The edit and delete event of this child is working is fine.When i add data to through child gridview with empty data template.i can 't find the value of the parent contril id.

gvProductFeatures is the chid gridview...
protected void gvProductFeatures_RowCommand(object sender, GridViewCommandEventArgs e)
{
try
{
if (e.CommandName.Equals("EmptyAddNewFeature"))
{
GridView gv = (GridView)sender;
if (gv != null)
{
// here i need find the appropriate control id from parent..how??
int intIndex = Convert.ToInt32(e.CommandArgument);
Label lblEmptyGroupPK = (Label)gv.Controls[0].Controls[0].FindControl("lblEmptyGroupPK");
TextBox txtEmptyFeatures = (TextBox)gv.Controls[0].Controls[0].FindControl("txtEmptyFeatures");
}
}
}
catch(Expection ex)
{
}
}